Ultrasonic wave nebulizer

ABSTRACT

An ultrasonic wave nebulizer according to the present invention comprises a nebulizing chamber containing a liquid to be nebulized and capable of adjusting the surface level of said liquid to a predetermined value, a chamber base disposed at the bottom portion of said nebulizing chamber, a piezo-electric transducer mounted on said chamber base in such a manner that its vibration surface has an inclination of 2*-22* with respect to said surface level of said liquid, a pair of transistors for ultrasonically oscillating the transducer and directly mounted on said chamber base, a conical horn having a predetermined reflection surface and being located on the upper portion of said piezo-electric transducer which makes contact with the bottom portion of said liquid, an exhaust cylinder or duct for exhausting fog composed of minute liquid particles and formed in said nebulizing chamber, and an air supply inlet for guiding or flowing said fog to the generating direction of said fog whereby the effective nebulized amount of said liquid per unit input electric power can be increased, so that a high nebulizing efficiency can be provided.

United States Patent [1 1 Mitsui et al.

[451 Aug. 26, 1975 ULTRASONIC WAVE NEBULIZER [73] Assignee: TDKElectronics Co., Ltd., Tokyo,

Japan 22 Filed: Jan. 7, 1974 211 Appl. No.: 431,202

[30] Foreign Application Priority Data Feb. 6, 1973 Japan 48-15459 Feb.12, 1973 Japan 48-17601 Feb. 12, 1973 Japan.... 48-17602 Aug. 31, 1973Japan 48-103005 [52] US. Cl 239/102; 239/338 [51] Int. Cl. B05B 3/14[58] Field of Search 239/101, 102, 338

[56] References Cited UNITED STATES PATENTS 3,243,122 3/1966 Snaper239/102 3,469,785 9/1969 Boucher et al. 239/102 3,472,455 10/1969Johnson et al.. 239/338 3,525,476 8/1970 Boling et al..... 239/3383,589,606 6/1971 Fish 239/338 Primary ExaminerLl0yd L. King Attorney,Agent, or FirmBurgess, Ryan and Wayne 5 7] ABSTRACT An ultrasonic wavenebulizer according to the present invention comprises a nebulizingchamber containing a liquid to be nebulized and capable of adjusting thesurface level of said liquid to a predetermined value, a chamber basedisposed at the bottom portion of said nebulizing chamber, apiezo-electric transducer mounted on said chamber base in such a mannerthat its vibration surface has an inclination of 222 with respect tosaid surface level of said liquid, a pair of transistors forultrasonically oscillating the transducer and directly mounted on saidchamber base, a conical horn having a predetermined reflection surfaceand being located on the upper portion of said piezoelectric transducerwhich makes contact with the bottom portion of said liquid, an exhaustcylinder or duct for exhausting fog composed of minute liquid particlesand formed in said nebulizing chamber, and an air supply inlet forguiding or flowing said fog to the generating direction of said fogwhereby the effective nebulized amount of said liquid per unit inputelectric power can be increased, so that a high nebulizing efficiencycan be provided.

8 Claims, 11 Drawing Figures AIR INLET PATENTEB A1182 61975 SHEET 1 [1FPATENTEDAUBZBIQYE I 3.901.443

sum 2 OF 5 Fig. 2

PATENTEDAUGZBIHYS R801 4-43 SHEET 3 OF AAA PATENTED EZ IQYS sum 5 n; 6

INPUT POWER P (w) ULTRASONIC WAVE NEBULIZER The present inventionrelates to an apparatus for nebulizing various liquids utilizing anultrasonic wave in which the effective nebulized amount of the liquidper unit of input electric power can be increased.

BACKGROUND OF THE INVENTION It is well known that in the conventionalultrasonic wave nebulizer, an ultrasonic wave is injected into a liquidfrom beneath the surface thereof toward the vertical upward direction,whereby a continuously spouting column of liquid is formed in theinjecting direction, and the desired minute liquid particles can beproduced and nebulized at a position adjacent to the top end portion ofthe liquid column. However, such an ultrasonic wave nebulizer as used inthe conventional art has objectionable features as described below.

a. The vibration surface of the transduucer for generating a supersonicwave is attached to the bottom portion of the nebulizing chamber inparallel with the surface of the liquid in the nebulizing chamber sothat a continuous stream liquid column is formed in a direction verticalto the liquid surface, and large liquid parti cles and water drops whichare not being nebulized are produced in an area adjacent to the top endportion of said continuously spouting liquid column, and intermittentlyfall down therefrom. As a result of this, the form of the continuouslygenerating and spouting liquid column is disturbed and nebulization atthe abovementioned adjacent position is decreased, so that a fog ofminute liquid particles is intermittently produced.

b. Generally, the transducer of the nebulizer is driven by one to fourtransistors with an output power of 15 to 50 watts. In this case, as iswell known, it is necessary to disperse the heat generated in eachtransistor during its operation so as to operate the transistornormally. Consequently, in the prior art, a natural air cooling means isutilized for dispersing the heat generated in the transistor into theatmosphere, such as a cooling fan exclusively used for the transistor,or other oscillating frames having a heat dispersing structure. However,according to this natural air cooling method, it is necessary to enlargethe construction of both the heat disperser and entire nebulizer.

c. The relationship between a liquid surface level L (cm), that is thedistance between the supersonic wave source and the liquid surface, anda nebulized amount of the liquid Q (cc/hr) is as follows. When theliquid surface level L is in a range of from to 8.0 cm. a sufficientnebulizing capacity can be obtained, and the more preferable conditionsare when the liquid surface level L is from to 7.5 cm, the frequency is1.3 MHz and the diameter of the source is 25. However, to keep theliquid surface level L approximately at a constant value, it isnecessary to use an additional liquid supply pump or a liquid surfacedetector, but in either case, a driving power source or an additionalelectron circuit is needed.

d. Further, in a conventional supersonic wave nebulizer, since thelargest part of an air stream around the spouting liquid formed in thenebulizing chamber flows vertically upward, parallel to the formingdirection of the spouting liquid and some part of which flows in theopposite direction, the amount of fog flowing to the exterior of thechamber, inevitably becomes less than that of the generated fog.

SUMMARY OF THE INVENTION The principal object of the present inventionis to eliminate the above-mentioned conventional objectionable featuresand greatly increase the nebulized amount of liquid.

The first characteristic feature of the present invention is that apiezo-electric transducer is mounted on the horizontal bottom portion ofa nebulizing chamber containing a liquid to be nebulized by saidpiezoelectric transducer in such a manner than its vibration surface hasa predetermined inclination with respect to the surface of said liquid,so as to continuously form a liquid column spouting stream in adirection inclined to said liquid surface. As a result, large liquidparticles and water drops not being nebulized, produced at a positionadjacent to the top end portion of said liquid column, are preventedfrom dropping therethrough.

The second characteristic feature of the present invention is that aconical horn having a predetermined reflection surface is provided onthe upper portion of said piezo-electric transducer in contact with theliquid to be nebulized.

The third characteristic feature of the present invention is that theheat produced by transistors is dispersed by a metallic chamber base ofthe nebulizer and by a water cooling means utilizing the liquid or waterto be nebulized as a coolant, so that the constructions of both the heatdisperser and the entirenebulizer can be miniaturized.

The fourth characteristic feature of the present in vention is thatmeans are provided for maintaining a distance between the ultrasonicwave source and the liquid surface, that is, the liquid surface level,is kept approximately at a constant value.

The fifth characteristic feature of the present invention is the all theproduced fog can be expelled from the nebulizing chamber by arrangingthe direction of the air flow around the generating portion of the fogapproximately parallel to the direction of the water spout produced bythe transducer is formed the forming direction of the spouting water.

BRIEF EXPLANATION OF THE DRAWINGS Further features and advantages of thepresent invention will be apparent from the ensuing description withreference to the accompanying drawings to which, however, the scope ofthe invention is in no way limited.

FIG. 1 is a cross-sectional view, along Il, of FIG. 2, of one embodimentof a nebulizer according to the present invention, showing the assemblythereof;

FIG. 2 is a bottom view of the nebulizer shown in FIG. 1;

FIG. 3 is a cross-sectional front view of the piezoelectric transducerincluded in FIG. 1, illustrating its mounting portion in detail;

FIG. 4 is an ultrasonic wave oscillation and amplification circuitdiagram for driving the piezo-electric transducer used in FIG. 1;

FIGS. 5 and 6 are respectively characteristic curves of the nebulizershown in FIG. 1;

FIG. 7 is a cross-sectional front view of another embodiment of thenebulizer according to the present invention;

FIG. 8 is a characteristic curve of the nebulizing apparatus shown inFIG. 7;

FIGS. 9 and 10 are respectively modified embodiments of the nebulizeraccording to the present invention, and;

FIG. 11 is a photoelectric circuit connection diagram used in FIG. 10.

FIRST EMBODIMENT ACCORDING TO THE PRESENT INVENTION As shown in FIG. 1,an ultrasonic wave nebulizer ac cording to the present inventioncomprises a nebulizing chamber 2 containing a predetermined amount ofliquid l, a piezo-electric transducer 4 inserted into a through hole 3formed at the bottom portion of said chamber 2 and tightly secured tothe bottom portion of the chamber 2 by means of a pair of thumb screws20 as shown in FIG. 3. Said piezo-electric transducer 4 is electricallydriven by an ultrasonic oscillation and amplification circuit shown inFIG. 4 with a natural frequency. A liquid or water column 5 in the shapeof a spouting stream is formed on the surface of said liquid 1 in adirection vertical to the transducer surface of said transducer 4, sothat water drops 6 such as large liquid particles and fogs 7, consistingof minute liquid particles, are produced at a position adjacent to thetop end portion of said water column 5. The fogs 7 so generated areforcibly expelled through an exhaust duct 9 mounted on the upper portionof the nebulizing chamber 2 by applying an air current from an airsupply inlet FIG. 2 is a bottom view showing the main elements of thenebulizer shown in FIG. 1. In FIG. 2, there is clearly shown a powertransformer 10, a pair of transistors 11 mounted on the bottom portionof the nebulizing chamber 2, a printed circuit plate -12 for mounting orsupporting said ultrasonic oscillation and amplification circuit shownin FIG. 4, a motor 13 for driving a fan 14, a power fuse 15, a powercord 16 and a power cord connector 16a.

FIG. 3 is a diagram showing, in detail, the elements for mounting orsecuring the piezo-electric transducer 4 shown in FIG. 1. In FIG. 3,there is clearly shown a piezo-electric transducer 4 (having a diameterof 20 d) and a thickness of 1.66 mm), a rubber support 17, an aluminumchamber base 18 of the nebulizing chamber 2, a cap 19 for securing thepiezo-electric transducer 4, a pair of thumb screws 20 for fastening thetransducer 4 and the supporting rubber 17 by securing the cap 19 of thedisc 4, and a pair of through holes 21a formed at the bottom portion ofthe liquid tank 21 shown in FIG. 1. Further, a pair of positive andnegative electrodes (not shown) are provided which are sintered on thetop surface of the transducer 4 and turned around from a part of the topsurface to the bottom surface of the transducer 4 and respectivelysoldered to lead wires (not shown).

FIG. 4 is an embodiment of an ultrasonic wave oscillation andamplification circuit diagram for driving the piezo-electric transducer4 used in the nebulizer shown in FIG. 1, according to the presentinvention. The circuit comprises: an oscillator or oscillation circuitcomposed of a transistor an inductance coil L capacitors C C andresistors R R a buffer amplifier, composed of a transistor Q a tuningcircuit of C and T capacitors C and C and resistors R R a poweramplifier, composed of a transistor Q an emitter resistor R and a tuningcircuit of C and T An oscillatory output of the oscillator is suppliedvia a coupling condenser C to the buffer amplifier, via a couplingresistor R to the power amplifier, and then to the piezoelectrictransducer 4 shown in FIG. 1. Rectifiers D, D and a condenser C composea rectifier bridge circuit, and a resistor R and condensers C C composea smoothing circuit.

The characteristic features of the ultrasonic wave nebulizer having theabove-mentioned construction as shown in FIGS. 1 through 3, according tothe present invention, will hereinafter be illustrated in detail.

As shown in FIG. I, the surface of the piezo-electric transducer 4 isnot arranged in parallel with the surface of the liquid 1, but ismounted on a bottom portion of the nebulizing chamber 2 in such a mannerthat its vibration surface has a predetermined inclination 9 withrespect to the surface of the liquid 1. Consequently, the water column 5in the shape of the spouting stream is continuously formed on thesurface of the liquid 1 with a certain inclination to the surface of theliquid 1. In this case, water drops such as large liquid particles arescattered from the tip end portion of the water column 5 and drop downonto a position separated from said tip end portion of the water column5. As a result of the above, said water column 5 is steadily formed onthe surface of the liquid 1, and the liquid 1 is continuously nebulizedby the pieZo-electric transducer 4. FIG. 5 is an experimental resultshowing a change in the amount of the nebulized water when theinclination angle 6 of the vibration surface of the piezo-electrictransducer 4 with respect to the surface of the water 1 was changed from0 to more than while maintaining the exciting or driving power of thepiezo-electric transducer 4 at a constant value of W. As is clear fromFIG. 5, the nebulizing capacity can be enhanced about 23% when theinclination angle 9 is in a range of from 2 to 22. Further, it was foundthat when the inclination angle 0 was increased more than 22, thereflection of the ultrasonic wave on the liquid or water surface wasincreased, while the nebulizing capacity was decreased.

As shown in FIG. 2, since the transistors 11 are directly attached tothe surface of the chamber base 18 of the nebulizing chamber 2, thetransistors 11 are effectively cooled by the water 1 by way of thechamber base 18.

Generally, the temperature of the water 1 rises to approximately C,however, if cool water is injected into the nebulizing chamber 2 duringthe generation of fog, the cooling effect on the transistors 11 isfurther raised.

Further, as shown in FIG. 1, in the ultrasonic nebulizer, the liquidtank 21 is provided in such a manner that its surface level becomesequal to the surface level of the water 1 in the nebulizing chamber 2 sothat the nebulization of the liquid 1 can be continuously carried outfor many hours. Generally, the relationship between the liquid surfacelevel L (cm), that is, the distance between the ultrasonic wavetransducer 4 and the surface of the liquid 1, and the nebulized amount Q(cc/hr) of the liquid 1 is shown in FIG. 6. As is clear from FIG. 6,when the liquid surface level L is in a range from 0 to 8.0 cm, asufficient nebulizing capacity can be obtained, and the more preferableconditions are when the liquid surface level L is 5 7.5 cm, thefrequency is 1.3 MHz and the diameter of the piezoelectric transducer is25 d).

In the above-mentioned embodiment, the bottom portion of the exhaustingduct 9 for air and fog 7 is disposed adjacent to the upper surface ofthe liquid 1 so as to insert the fog generating front portion of thewater column 5 into the exhaust duct 9. The air supplied from the airsupply inlet 8 flows through a passage formed between the inside wall ofthe nebulizing chamber 2 and the outside wall of the exhaust cylinder 9and is guided adjacent to the surface of the liquid 1 in the nebulizingchamber 2. The air then flows upwardly into the exhaust cylinder 9,while the air around the fog generating front portion of the watercolumn 5 flows in the same direction as the water column. Thus, the air,together with fog 7, are expelled through the exhaust cylinder 9 to theexterior of its nebulizer. As a result, the generation of fog 7 from thefront portion of the water column 5 is not restricted by the pressure ofthe air and, also, the air flow in the above-mentioned passage formedbetween the inside wall of the nebulizing chamber 2 and the outside wallof the exhaust cylinder 9 is not disturbed. Consequently, the amount ofwater drops caused by the adherence of the fog 7 to the inside wall ofthe exhaust cylinder 9 decreases, so that the fog transmittingefficiency is enhanced. Further, under a condition of absence of airflow, since the generated fog 7 is floating around the water column 5,the water column 5 is gradually surrounded by the floating fog 7 and,therefore, it is difficult to generate a fog 7 of minute liquidparticles, but a fog 7 of large liquid particles is likely to beproduced. However, by flowing the air as mentioned before, a fog 7 ofminute liquid particles of a constant small size is easily produced andthis produced fog 7 is effectively expelled. Also, since the directionof the air flow and the formation direction of the water column is thesame, even if the velocity of the air flow is increased to some extent,the top portion of the water column 5 is not scattered.

An effect of the nebulizer according to the present invention will beclearly understood from the following experimental result. Thisexperiment was carried out at normal temperature and normal pressure,with a constant ultrasonic wave frequency and a constant ultrasonic waveintensity, and a constant amount of air was supplied from the air supplyinlet 8. In this experiment, the measured amount Q (cc/hr) of fog 7extruded from the exhaust duct or cylinder 9 was l,400 cc/hr, while thatof the conventional nebulizer is 600 650 cc/hr.

SECOND EMBODIMENT ACCORDING TO THE PRESENT INVENTION In an ultrasonicwave nebulizer constructed as shown in FIG. 1, an oscillatory frequencyf (Hz) having a wave length of k (mm) transmitted through an optionalmedium at a velocity of V (m/s) is expressed by the equation:

A suitable frequency f for nebulizing the liquid is preferably in arange from 0.8 to 2.0 MHz, and when water is utilized as a medium, thewave length A becomes approximately O.75 1.90 mm. In such a range of thewave length A, to transmit the oscillation of the oscillator 4 throughthe medium with a high efficiency, a conical horn 22 is provided betweenthe bottom of the nebulizing chamber 2 and the top of the transducer 4as shown in FIG. 7. It is possible to obtain a sharp directivity bysuitably selecting the angle of inclination of the conical horn 22. Therelationship between an input power P (W) and a nebulized amount Q(cc/hr) of the liquid in this second embodiment is graphically shown inFIG. 8. When the horn 22 is not provided, the curve is as shown by abroken line in FIG. 8. That is, according to the nebulizer of thepresent invention, provided with the horn 22, the nebulizing efflciencycan be increased or improved by approximately 10 15%.

SEVERAL MODIFIED EMBODIMENTS ACCORDING TO THE PRESENT INVENTION In theabove-mentioned ultrasonic nebulizer of the first embodiment shown inFIG. 1, the liquid tank 21 is provided in such a manner that its surfacelevel becomes equal to that of the nebulizing chamber 2 so as tomaintain the liquid surface level L at a constant value with respect tothe ultrasonic transducer 4. Next, other modified embodiment formaintaining the liquid surface level L at a constant value will beexplained.

FIG. 9 is a first modified embodiment for maintaining the surface levelL of the liquid 1 contained in the nebulizing chamber 2 at a constantvalue. When the transducer 4, mounted on the bottom portion of thenebulizing chamber 2, is excited by an electric circuit, the liquid 1contained in the nebulizing chamber 2 is nebulized and then expelledthrough the exhaust duct 9 to the exterior by the air flow produced bymeans of the fan 14. Consequently, the amount of the liquid 1 containedin the nebulizing chamber 2 decreases. However, the liquid contained ina liquid tank 27 is pushed upward by means of, for example, a propellerpump 23 connected to the fan 14, and then the liquid corresponding tothe above-mentioned decreased amount is supplied from a water supplyinlet 24 into said nebulizing chamber 2. In this case, the amount of theso supplied liquid is somewhat in excess of the amount of the nebulizedand exhausted liquid, and the extra amount of the supplied liquid isreturned to the liquid tank 27 from a vertical over-flow pipe 26 via anoverflow portion 25. Thus, the surface level L of the water 1 containedin the nebulizing chamber 2 can be maintained at a constant value by theliquid supply means.

FIG. 10 is a second modified embodiment for maintaining the liquidsurface level L at a constant value. A nebulizer shown in FIG. 10comprises the nebulizing chamber 2 and the transducer 4 mounted on thebottom portion of the nebulizing chamber 2. Water is fed into thenebulizing chamber 2 via a suitable water supply inlet 24. Further,there is provided a pair of electrodes 28, 29 in the nebulizing chamber2. The electrode 28 is situated at a position where the surface level Lof the water 1 in the nebulizing chamber 2 can be maintained at anydesired position. The other electrode 29 is disposed at a lower criticalposition where serious trouble, for example, damage to the nebulizingchamber 2 is liable to be produced by some cause when liquid surfacelevel L is lowered beyond the abovementioned lower position.

The pair of electrodes 28 and 29 are connected to an electric powersource or circuit 30 via respective condensers C and C and thenebulizer. An AC voltage suitable for operating the electric circuit ofFIG. 10 is impressed between the pair of nebulizer and the electrodes 28and 29. Further, first and second neon lamps 31 and 32 are providedbetween the electrodes 28, 29 and the nebulizer, respectively. A bridge33 and a smoothing condenser C respectively contained in the powercircuit 30 are used for supplying DC currents to a pair of first andsecond photoelectric circuits 34 and 35.

When the surface level L of the liquid 1 in the nebu lizing chamber 2drops below the lower end of the electrode 28, the electrode 28 isexposed to the air. As a result, the potential difference between theexposed electrode 28 and the nebulizer increases, so that the first neonlamp 31 is lighted. Similarly, when the surface level L drops below thebottom end of the electrode 29, the second neon lamp 32 is also lighted.

Said first and second photoelectric circuits 34 and 35 are actuated byreceiving light radiated from the first and second neon lamps 31 and 32,respectively. These first and second photoelectric circuits 34 and 35are respectively constructed as shown in FIG. 11. That is, eachphotoelectric circuit 34 or 35 has a photoelectric element 36 (forexample, cadmium sulfide cds) placed at a position where the lightradiated from the each neon lamp 31 or 32 can be received. When thephotoelectric element 36 receives luminous flux beyond a predeterminedvalue, a voltage supplied to a base of a transistor Q via a resistor Ris decreased, so that the transistor Q, is turned off. As a result ofthis, the potential of a collector of the transistor Q rises inaccordance with the time constant of a resistor R and a condenser C anda transistor O is turned on. Further, a zener diode ZD inserted betweenthe collector of the transistor Q and a base of the transistor Q servesto maintain the impedance of the transistor Q viewed from the transistorQ side, at a high value during the time the transistor O is off, andsecure the switching operation of the transistor Q When a transistor Ois turned on, a current flows in an exciting coil of a relay 37, so thatthe relay 37 is brought into an operating condition. The relay 37controls a switch of a supply mechanism for supplying water into thenebulizing chamber 2 via the water supply inlet 24 shown in FIG. 9. Whenthe liquid surface level L in the nebulizing chamber 2 rises to theposition of the electrode 28, the first neon lamp 31 is extinguished dueto the potential drop of the electrode 28. As a result of this, thetransistor 0., of the photoelectric circuit 34 is turned on andenergized and the transistor O is turned off and deenergized, so thatthe relay 37 returns to its non-operational condition and the supply ofwater into the nebulizing chamber 2 is stopped. By repeating theabove-mentioned operation, the liquid surface level L can always bemaintained within a predetermined range.

Further, when the liquid surface level L is lowered by some accidentbeyond the bottom end of the electrode 29, the second neon lamp 32lights and this is detected by the second photoelectric circuit 35, sothat the relay 37 is actuated and the operation of the nebulizer isstopped.

What is claimed is:

1. An ultrasonic wave nebulizer comprising a nebulizing chamber filledwith a predetermined amount of liquid, a chamber base formed at thebottom portion of said nebulizing chamber, a piezo-electric transducerinserted into and secured to said chamber base so that the vibrationsurface of said piezo-electric transducer has an inclination of 2 22with respect to the surface of said liquid in said nebulizing chamber,an electric circuit means for electrically oscillating said transducerwith a natural frequency thereof, an exhaust duct for expelling fogcomposed of minute liquid particles and formed above said vibrationsurface of said transducer to the exterior, and an air supply inlet forsupplying an air flow to said fog thereby forcibly expelling said fogthrough said exhaust cylinder.

2. A nebulizer as claimed in claim 1, further comprising a conical hornhaving a predetermined reflection surface provided on the upper portionof said transducer contacting said liquid to be nebulized.

3. A nebulizer as claimed in claim 1, further comprising transistors forultrasonically driving said transducer directly attached to said chamberbase and cooled by said water used for producing said fogs via saidcharnber base.

4. A nebulizer as claimed in claim 1, further comprising a means formaintaining the surface level of said liquid in said nebulizing chamberat a constant value.

5. A nebulizer as claimed in claim 4, further comprising a liquid tank,and means for maintaining the liquid surface level of said liquid tankequal to the surface level of said liquid in said nebulizing chamber.

6. A nebulizer as claimed in claim 5, wherein said liquid tank isdisposed in such a manner that said liquid surface level of said liquidtank is lower than said surface level of said liquid in said nebulizingchamber, said liquid is supplied from said liquid tank into saidnebulizing chamber by means of a pump and any excess amount of saidsupplied liquid is returned back into said liquid tank via an overflowportion connected to said nebulizing chamber.

7. A nebulizer as claimed in claim 4, further comprising a pair of firstand second electrodes respectively contained in said nebulizing chamberand situated with a vertical space within a range of variations of saidsurface level of said liquid in said chamber, said electrodes and thebottom portion of said chamber are respectively connected to an ACsource and an AC voltage is applied therebetween, a pair of firstand'second lamps respectively operate after detecting changes inpotentials caused by variations of said liquid surface level beyond saidpositions of said electrodes, and a pair of first and secondphotoelectric circuits being actuated by the lights radiated from saidlamps, respectively, so that said liquid surface level in saidnebulizing chamber can be detected.

8. A nebulizer as claimed in claim 1, wherein said air supply inletpoints in the direction of said rising column of fog said fog assumingthe shape of a water column formed on said liquid surface in saidnebulizing chamber, whereby said fog is sent to the exterior along thedirection of said air flow.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,901,443 Dated August 26,1975

Inventcr s) Sadao Mitsui, et a] It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

In the Abstract, line 9: delete "a pair of".

Column 8, line 55: replace "said" by -a-.

line 56: insert a comma after "fog".

Signed and Scaled this eighteenth D2) of May 1976 [SEAL] A nest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissinm'r nj'lalemsand Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,901,443 Dated ugust 26, 1975 Inventor(g) Sadao Mitsui, eta1 It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, lines 42 and 43: Please delete "is formed the formingdirection of the spouting water".

Signed and Scaled this ninth Day of March 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oflaremsand Trademarks

1. An ultrasonic wave nebulizer comprising a nebulizing chamber filledwith a predetermined amount of liquid, a chamber base formed at thebottom portion of said nebulizing chamber, a piezoelectric transducerinserted into and secured to said chamber base so that the vibrationsurface of said piezo-electric transducer has an inclination of 2* - 22*with respect to the surface of said liquid in said nebulizing chamber,an electric circuit means for electrically oscillating said transducerwith a natural frequency thereof, an exhaust duct for expelling fogcomposed of minute liquid particles and formed above said vibrationsurface of said transducer to the exterior, and an air supply inlet forsupplying an air flow to said fog thereby forcibly expelling said fogthrough said exhaust cylinder.
 2. A nebulizer as claimed in claim 1,further comprising a conical horn having a predetermined reflectionsurface provided on the upper portion of said transducer contacting saidliquid to be nebulized.
 3. A nebulizer as claimed in claim 1, furthercomprising transistors for ultrasonically driving said transducerdirectly attached to said chamber base and cooled by said water used forproducing said fogs via said chamber base.
 4. A nebulizer as claimed inclaim 1, further comprising a means for maintaining the surface level ofsaid liquid in said nebulizing chamber at a constant value.
 5. Anebulizer as claimed in claim 4, further comprising a liquid tank, andmeans for maintaining the liquid surface level of said liquid tank equalto the surface level of said liquid in said nebulizing chamber.
 6. Anebulizer as claimed in claim 5, wherein said liquid tank is disposed insuch a manner that said liquid surface level of said liquid tank islower than said surface level of said liquid in said nebulizing chamber,said liquid is supplied from said liquid tank into said nebulizingchamber by means of a pump and any excess amount of said supplied liquidis returned back into said liquid tank via an overflow portion connectedto said nebulizing chamber.
 7. A nebulizer as claimed in claim 4,further comprising a pair of first and second electrodes respectivelycontained in said nebulizing chamber and situated with a vertical spacewithin a range of variations of said surface level of said liquid insaid chamber, said electrodes and the bottom portion of said chamber arerespectively connected to an AC source and an AC voltage is appliedtherebetween, a pair of first and second lamps respectively operateafter detecting changes in potentials caused by variations of saidliquid surface level beyond said positions of said electrodes, and apair of first and second photoelectric circuits being actuated by thelights radiated from said lamps, respectively, so that said liquidsurface level in said nebulizing chamber can be detected.
 8. A nebulizeras claimed in claim 1, wherein said air supply inlet points in thedirection of said rising column of fog said fog assuming the shape of awater column formed on said liquid surface in said nebulizing chamber,whereby said fog is sent to the exterior along the direction of said airflow.